A electronic or hard-copy table or listing of the predicted positions of astronomical bodies such as the planets or the Moon; and by extension, the predicted positions of artificial satellites, such as communications satellites, orbiting the Earth. Plural ephemerides. Note 1: Ephemerides are essential tools for accurate aiming of movable high-gain antennas at, e.g., communications satellites, especially ones that exhibit significant movement relative to a fixed position on the Earth. Note 2: Precise ephemerides of the satellites used in global navigation systems, such as GPS, are required for the proper functioning of these systems.